Known stands for surgical microscopes comprise a suspension apparatus that encompasses a total of three movable carriages. In particular, a so-called A carriage, a B carriage, and a C carriage are provided, so that a motion in all three spatial directions is possible. The carriages are moved in this context via motors, a separate motor being provided to move each carriage.
In addition to automatic counterbalancing, the individual carriages can also be displaced manually; a toggle switch with which the pertinent carriage can be displaced in both of its directions in order to effect a new counterbalancing operation, or for balance adjustment, is provided for each carriage on the arm pertinent thereto.
A possible counterbalancing mechanism for a surgical microscope stand is commonly known to one skilled in the art and will not be described in further detail here.
These known stands have the disadvantage that a pressure is exerted by each actuation of the toggle switch in the context of manual counterbalancing, thereby making accurate counterbalancing difficult. An elevated pressure upon actuation of the toggle switch is necessary in particular when the surgical microscope stand is enclosed by a so-called “drape,” with the result that manual counterbalancing can be accomplished only very inaccurately. The toggle switches moreover have the disadvantage that dirt can quickly become lodged in them, and they are difficult to clean in thoroughly hygienic fashion. A further disadvantage of these known stands is that depending on the position of the carrier arms of the suspension apparatus, the toggle switches are difficult to access, and in particular the toggle switches for different carriages are located at sites far apart from one another. This results in a space-intensive and motion-limiting configuration. A further disadvantage of these stands is that the motors usually can be actuated as desired with the carrier arms in any position, which can lead to overheating of the motors due to overload of the motors. The service life of the motors is thereby limited, and considerable noise emission can occur.